Here are a few ideas that might help with the chroma key method.

If you are getting bleeding on the fringes from the key color you can try rendering 2 versions of the picture one with the key color and one with black instead of the key color.  Use the one with the key color to make your selection and then delete the parts you don't want on the one with the black.  Black fringes aren't as noticeable as colored fringes.

Often when I make selection I do not use the magic wand but instead will duplicate one of the color channels, touch it up (make all the parts you want to mask pure black) and use it to make a selection. 

Using a chroma key color the has an R, G or B value at a maximum of 255 this works well with using one of the color channels form making the section.  For example if I'm using a key color with a blue value of 255 I would use the blue channel from making the selection.

Chris Cox